Fluorine-containing polyether compounds having functional groups at the terminals of molecule, for example, represented by the following general formula are known (Patent Document 1):

More general compounds obtained by oligomerizing the main chain structure of the afore-mentioned compounds and represented by the following general formula are also known (Patent Document 2):

It is disclosed that a series of compounds represented by these general formulae can give elastomeric moldings having much distinguished characteristics (chemical resistance, heat resistance, and low-temperature characteristics) by curing with a fluorine-containing organo hydrogen siloxane compound having a plurality of Si—H groups in the molecule in the presence of a platinum compound catalyst, and the moldings can be used particularly even at low temperatures such as about −50° C. without losing the flexibility. Curable compositions comprising these compounds as the main component have a remarkable molding processability and can undergo even RIM molding. However, the cured products have siloxane bonds in the intramolecular cross-linked structure, and thus may give undesirable effects such as chemical deterioration and the resulting lowered mechanical strength, when used in the presence of an acidic substance such as hydrogen fluoride, etc.